264 



GEOLOGY OK TONOPAH MINING DISTRICT, NEVADA. 



TEMPERATURES 



THE MONTANA TONOPAH. 



Some observations were also taken in the Mizpah and in the Montana Tonopah 

 workings, but with a less range of depth. Those in the Montana Tonopah, however, 

 were taken at intervals along the vertical shaft, in holes drilled for the purpose, 

 and the thermometers were left in place 15 minutes, check readings corresponding 

 exactly. They are, therefore, worthy of confidence, and are given in the following 



table: 



Temperatures in Montana Tonopah shaft. 



Average increase, 1 in 43.5 feet. 



Although the average increment of temperature (1 F. in 43.5 feet) for the 

 Montana Tonopah measurements differs from that shown by the Mizpah Extension 

 measurements (1 in 51.3 feet), comparison of the tables shows that the temperatures 

 for the corresponding levels in each case practically coincide. 



These separate temperature measurements have been plotted as curves (fig. 77). 

 The Mizpah Extension curve, as shown, is distinct from the Ohio Tonopah curve, 

 while the Montana Tonopah curve coincides with the corresponding portion of 

 the Mizpah Extension. 



TEMPERATURES IN MIZPAH HILL. WORKINGS. 



Six measurements were taken in the Mizpah Hill workings, but under less 

 exact conditions. They were taken at various points in the drifts, and so at 

 variable distances perpendicularly from the surface, sometimes in drilled holes 

 and sometimes at the ends of unventilated drifts. These mines, however, had, at 

 the time of examination, a thorough system of ventilation (which the others did 

 not) and the measurements do not check exactly, and indicate that the temperature 

 was affected by air currents. They are therefore not published. 



